Mobile communications terminal having key input error prevention function and method thereof

ABSTRACT

A mobile communications terminal and a method for preventing an input error of a key input unit are provided. The mobile communications terminal includes a touch sensor unit for sensing a key that is input by touching a keypad region in order to output a key input signal corresponding to the key and a controller adapted to determine a key input according to either a priority between multiple keys from which key signals are received or whether a received key signal was generated inadvertently.

CROSS-REFERENCE TO RELATED APPLICATIONS

Pursuant to 35 U.S.C. § 119(a), this application claims the benefit ofearlier filing date and right of priority to Korean Application No.10-2006-0028095, filed on Mar. 28, 2006, the contents of which is herebyincorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The present invention relates to a key input method of a mobilecommunications terminal, and specifically, to a mobile communicationsterminal having a function for preventing an input error of a touch-typekey input unit and a key input method thereof.

DESCRIPTION OF THE RELATED ART

In general, mobile communications terminals can support variousadditional functions such as Short Message Service (SMS) or chatting,web surfing, scheduling, memo or games as well as voice communicationand are provided with a keypad for controlling the functions. Althoughmobile communications terminals may have different designs, the keypadsgenerally function such that a contact point of each key is contactedwith a contact point pattern disposed on a print substrate of a terminalmain body upon pressing an upper portion of each key constituting thekeypad.

Accordingly, a related art mobile communications terminal having akeypad that functions according to the general pressing method has adisadvantage in that an excessive force is applied to a user's fingerupon pressing a key. In order to solve the problem, touch-type keypadshave recently been used in mobile communications terminals.

However, unlike a keypad utilizing the “pressing method”, touch-typekeypad may have a disadvantage in that an unintended key function isinput by simply contacting keys on the keypad. The potential to input anunintended key function makes it difficult to arrange keys at narrowerintervals, thereby complicating efforts to miniaturize the mobilecommunications terminal.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a method for preventinga key input error generated when keys of a touch-type key input unit arearranged at narrow intervals and a mobile communications terminal havinga key input error prevention function for a touch-type key input unit.

In one aspect of the present invention, a method for detecting a keyinput in a mobile communication terminal having a plurality of touchkeys is provided. The method includes detecting an input signalcorresponding to two or more of the plurality of touch keys anddetermining one of the two or more touch keys as the key input accordingto a priority of the two or more touch keys.

It is contemplated that determining one of the two or more touch keys asthe key input includes determining a pre-assigned priority of each ofthe two or more touch keys and determining the touch key of the two ormore touch keys that has the highest priority as the key input. It isfurther contemplated that the pre-assigned priority of each of the twoor more touch keys is derived from statistical analysis.

It is contemplated that the pre-assigned priority of each of the two ormore touch keys is determined according to a position of the pluralityof touch keys on a keypad of the mobile communication terminal. It isfurther contemplated that the plurality of touch keys are arranged onthe keypad in at least two rows and the priority of each of plurality oftouch keys is pre-assigned such that a first touch key in an uppermostrow has higher priority than a second touch key in a lower row if thefirst and second touch keys are located in different rows.

It is contemplated that the plurality of touch keys are arranged on thekeypad in at least two columns and the priority of each of the pluralityof touch keys is pre-assigned such that a directional navigation touchkey has higher priority than a non-directional navigation touch key ifthe directional navigation touch key and non-directional navigationtouch key are located in the same row, It is further contemplated thatdetermining one of the two or more touch keys as the key input includesmeasuring a time for the input signal corresponding to each of the twoor more touch keys to reach a reference level and determining the touchkey of the two or more touch keys having the shortest measured time asthe key input. Preferably, determining one of the two or more touch keysas the key input further includes determining that the level of theinput signal corresponding to at least one of the two or more touch keysvaries within a predetermined range and measuring the time for theaverage level of the input signal corresponding to the at least one ofthe two or more touch keys to reach the reference level.

In another aspect of the present invention, a method for detecting a keyinput in a mobile communication terminal having a plurality of touchkeys is provided. The method includes determining that a task iscurrently being performed, identifying at least a first of the pluralityof touch keys that is not related to the task currently being performedand at least a second of the plurality of touch keys that is related tothe task currently being performed, adjusting a sensitivity levelassociated with the identified first touch key to be lower than asensitivity level associated with the second touch key, detecting aninput signal corresponding to one of the plurality of touch keys anddetermining whether the touch key corresponding to the detected inputsignal is a key input according to a sensitivity level associated withthe touch key.

It is contemplated that determining whether the touch key correspondingto the detected input signal is a key input includes measuring a periodof time that the input signal is continuously maintained above athreshold level corresponding to the touch key and determining the touchkey corresponding to the detected input signal as a key input only ifthe measured period of time exceeds a period of time corresponding tothe sensitivity level associated with the touch key. It is furthercontemplated that adjusting the sensitivity level associated with theidentified first touch key includes adjusting a time thresholdcorresponding to the identified first touch key such that the timethreshold is greater than a time threshold corresponding to theidentified second touch key.

It is contemplated that adjusting the sensitivity level associated withthe identified first touch key includes adjusting a level thresholdcorresponding to the identified first touch key such that the levelthreshold is greater than a level threshold corresponding to theidentified second touch key. It is further contemplated that measuringthe period of time the input signal is continuously maintained above thethreshold level includes determining that the level of the input signalvaries within a predetermined range and measuring a period of time thatthe average input signal level is continuously maintained above thethreshold level.

In another aspect of the present invention, a method for detecting a keyinput in a mobile communication terminal having a plurality of touchkeys is provided. The method includes detecting an input signalcorresponding to one of the plurality of touch keys, measuring a timefor the detected input signal to reach a threshold level, calculating agradient for the detected input signal using the measured time anddetermining the touch key corresponding to the detected input signal asa key input only if the calculated gradient is greater than apredetermined gradient. Preferably, calculating the gradient comprisesdividing the reference level by the measured time.

In another aspect of the present invention, a mobile communicationterminal is provided. The terminal includes a key pad having a pluralityof touch keys located thereon and a controller adapted to detect aninput signal corresponding to two or more of the plurality of touch keysand determine one of the two or more touch keys as a key input accordingto a priority of the two or more touch keys.

It is contemplated that the plurality of touch keys are arranged on thekeypad in at least two rows. It is further contemplated that a priorityof each of the plurality of touch keys is determined according to alocation of each of the plurality of touch keys on the keypad.

It is contemplated that the determined priority is derived fromstatistical analysis. It is further contemplated that the terminalfurther includes a memory adapted to store the determined priority ofeach of the plurality of touch keys.

It is contemplated that the controller is further adapted to determine apre-assigned priority of each of the two or more touch keys anddetermine the touch key of the two or more that has the highest priorityas the key input. It is further contemplated that the pre-assignedpriority of each of the two or more touch keys is derived fromstatistical analysis.

It is contemplated that the pre-assigned priority of each of the two ormore touch keys is determined according to a position of the pluralityof touch keys on the keypad. It is further contemplated that theplurality of touch keys are arranged on the keypad in at least two rowsand the priority of each of plurality of touch keys is pre-assigned suchthat a first touch key in an uppermost row has higher priority than asecond touch key in a lower row if the first and second touch keys arelocated in different rows.

It is contemplated that the plurality of touch keys are arranged on thekeypad in at least two columns and the priority of each of the pluralityof touch keys is pre-assigned such that a directional navigation touchkey has higher priority than a non-directional navigation touch key ifthe directional navigation touch key and non-directional navigationtouch key are located in the same row. It is further contemplated thatthe controller is further adapted to measure a time for the input signalcorresponding to each of the two or more touch keys to reach a referencelevel and determine the touch key of the two or more touch keys havingthe shortest measured time to reach the reference level as the keyinput.

It is contemplated that the controller is further adapted to determinethat the level of the input signal corresponding to at least one of thetwo or more touch keys varies within a predetermined range and measurethe time for the average level of the input signal corresponding to theat least one of the two or more touch keys to reach the reference level.It is further contemplated that the controller is further adapted todetermine that a task is currently being performed, identify at least afirst of the plurality of touch keys that is not related to the taskcurrently being performed and at least a second of the plurality oftouch keys that is related to the task currently being performed, adjusta sensitivity level associated with the identified first touch key to belower than a sensitivity level associated with the second touch key,detect an input signal corresponding to one of the plurality of touchkeys and determine whether the touch key corresponding to the detectedinput signal is a key input according to a sensitivity level associatedwith the touch key.

It is contemplated that the controller is further adapted to measure aperiod of time that the input signal is continuously maintained above athreshold level corresponding to the touch key and determine the touchkey corresponding to the detected input signal as a key input only ifthe measured period of time exceeds a period of time corresponding tothe sensitivity level associated with the touch key. It is furthercontemplated that the controller is further adapted to adjust a timethreshold corresponding to the identified first touch key such that thetime threshold is greater than a time threshold corresponding to theidentified second touch key.

It is contemplated that the controller is further adapted to adjust alevel threshold corresponding to the identified first touch key suchthat the level threshold is greater than a level threshold correspondingto the identified second touch key. It is further contemplated that thecontroller is further adapted to determine that the level of the inputsignal varies within a predetermined range and measure a period of timethat the average input signal level is continuously maintained above thethreshold level.

It is contemplated that the controller is further adapted to detect aninput signal corresponding to one of the plurality of touch keys,measure a time for the detected input signal to reach a threshold level,calculate a gradient for the detected input signal using the measuredtime and determine the touch key corresponding to the detected inputsignal as a key input only if the calculated gradient is greater than apredetermined gradient. It is further contemplated that the controlleris further adapted to calculate the gradient by dividing the referencelevel by the measured time.

The foregoing and other objects, features, aspects and advantages of thepresent invention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings. Additional features and advantages of theinvention will be set forth in the description which follows, and inpart will be apparent from the description, or may be learned bypractice of the invention.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed. These and other embodimentswill also become readily apparent to those skilled in the art from thefollowing detailed description of the embodiments having reference tothe attached figures, the invention not being limited to any particularembodiments disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention. In the drawings:

FIG. 1 is a block diagram illustrating a configuration of a mobilecommunications terminal having a touch-type key input unit according tothe present invention.

FIG. 2 illustrates a configuration of a touch-type key input unitaccording to the present invention.

FIG. 3 is a table illustrating results of experimental analysis of themost frequently generated key input errors that are considered inembodiments of the present invention.

FIG. 4 illustrates key arrangement of a keypad in accordance with anembodiment of the present invention.

FIG. 5 is a flow chart illustrating a key input error preventionalgorithm of a mobile communications terminal in accordance with a firstembodiment of the present invention.

FIG. 6 illustrates a lateral side of an end portion of a typical user'sfinger.

FIG. 7 illustrates a first key input method based upon the shape of atypical user's finger.

FIG. 8 illustrates a second key input method based upon the shape of atypical user's finger.

FIG. 9 illustrates a comparison of capacitance differences of signalsgenerated by contacting a touch-type keypad according to the presentinvention.

FIG. 10 is a flow chart illustrating a key input error preventionalgorithm of a mobile communications terminal in accordance with asecond embodiment of the present invention.

FIG. 11 illustrates a comparison of differences between key inputsignals generated based upon a contact time of a touch-type keypadaccording to the present invention.

FIG. 12 is a flow chart illustrating a key input error preventionalgorithm of a mobile communication terminal in accordance with a thirdembodiment of the present invention.

FIG. 13 is a flow chart illustrating a key input error preventionalgorithm of a mobile communications terminal in accordance with afourth embodiment of the present invention.

FIGS. 14A-C illustrate a comparison of a normal key input signal, staticelectricity and a noise signal.

FIG. 15 is a flow chart illustrating a key input error preventionalgorithm of a mobile communications terminal in accordance with a fifthembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Description of the present invention will now be given in detail withreference to the accompanying drawings. The present invention isdirected to a mobile communications terminal for preventing a key inputerror even when keys of the key input unit are arranged at narrowintervals by using a touch-type key input unit whereby an excessiveforce can be prevented from being applied to a user's finger uponcontacting keys.

FIG. 1 is a block diagram illustrating a configuration of a mobilecommunications terminal 100 having a touch-type key input unit accordingto the present invention. As illustrated in FIG. 1, a touch sensor unit101 is disposed under a keypad region at a surface of a main body case,thereby sensing a key that is input by touching the keypad region.

The touch sensor unit 101 preferably utilizes a capacitance sensingmethod to sense the key input since keys are usually input by a user'sfinger. However, the touch sensor unit 101 is not limited to capacitancemethod. The capacitance sensing method refers to a touch-sensingtechnique for accurately quantitatively detecting (sensing) capacitancegenerated by contact with a human body that is as small as several pF.

The keypad region does not refer to the keypad that is actually mountedon the mobile communications terminal, but rather to a region 200illustrated in FIG. 2 that represents functions and positions of keys atthe surface of the main body case of mobile communications terminal 100.As illustrated in FIG. 2, the keys do not denote actual buttons, butrather keypad regions 201 through 209.

The touch sensor unit 101 includes a plurality of touch sensors (notshown). The touch sensor corresponding to each key is mounted under thecorresponding keypad region 201-209. Accordingly, when a finger contactsa keypad region 201-209, a capacitance signal having a certain level isoutput from the touch sensor disposed under the corresponding keypadregion.

The capacitance signal output from the touch sensor unit 101 is input toa controller 105. The capacitance signal may be converted into a digitalsignal via an Analog to Digital (A/D) converter 102 before being inputto the controller 105. The A/D converter 102 may be mounted either inthe controller 105 or externally.

The controller 105 detects which of the plurality of touch sensors hasoutput the capacitance signal and determines that the key correspondingto the detected touch sensor has been input. The controller 105 thenperforms an operation assigned to the input key according to anoperation mode of the mobile communications terminal 100. For example,under the control of the controller 105, functions related to voicecommunication, text messaging, games and multimedia can be performed.The controller 105 also controls the display 104 to display informationrelated to the functions.

The mobile communications terminal 100 further includes a function forpreventing a key input error. In order to provide smaller mobilecommunications terminals to facilitate easier carrying, a smallerinterval between keys of an input keypad is preferred. Accordingly, whenthe interval between the keys of the keypad is narrower than a size of afinger, an unintended key located close to the intended key may beinput.

An algorithm for preventing a key input error is stored in a memory 103.When a key input is detected, the controller 105 uses the key inputerror prevention algorithm stored in the memory 103 to determine whethera key has been normally input or, in other words, whether a key the userdesires to select has been input. The controller 105 then controls adesignated operation corresponding to the input key only if a normal keyinput, or a key input that the user desires, has occurred.

The controller 105 determines the capacitance signal input through a keyinput signal detecting port (not shown) as a key input signal andcontrols a timer 106 to detect time information related to the key inputsignal. The key input error prevention algorithm will be explained indetail with reference to the attached drawings.

FIG. 3 is a table illustrating the results of experimental analysis ofthe most frequently generated key input errors according to embodimentsof the present invention. As illustrated in FIG. 3, upon inputting acertain key on a keypad having keys arranged at certain intervals, anerror ratio that a key located at a lower side of the certain key willbe simultaneously input with the certain key is the highest at 57%, anerror ratio that a key located at an upper side of the certain key willbe simultaneously input with the certain key is second highest at 23%and an error ratio that a key located at a left or right side of thecertain key will simultaneously input with the certain key is lowest at8%.

The simultaneous input of keys refers to a plurality of keys being inputwithin a holding time set to recognize that a key has been input anddoes not assume that the input time for each of the simultaneously inputkeys is the same. The table illustrated in FIG. 3 was generated byanalyzing key input errors generated from 198 tasks corresponding to 28%of a total of 339 tasks.

As illustrated in the table, 57% of the generated errors correspond toerrors where the key located at the lower side of the certain key issimultaneously input upon inputting the certain key. Furthermore, 63% ofthe generated errors where the lower side key is simultaneously inputcorrespond to errors where a key located at the very lower side of thecertain key is simultaneously input.

The tasks represented in FIG. 3 may include phone number registration,text message transmission, menu selection and setup, a game andmultimedia play among tasks performable in the mobile communicationsterminal. The key input error prevention algorithm according to a firstembodiment of the present invention is adapted to prevent the key inputerror by setting priorities for each key and determining a key having ahigher priority among two or more keys input as the input key.

Methods for setting priority will now explained with reference to thekey arrangement illustrated in FIG. 4. As illustrated in FIG. 4, thekeys are arranged in three lines and three columns with navigation keyslocated in the second column of the first line, the first column of thesecond line, a third column of the second line and the second column ofthe third line.

In a first method for setting priority when two keys located indifferent lines are simultaneously input, such as in the first line andthe second line or in the second line and the third line, a key arrangedat the uppermost line is set to have a higher priority. For example,when certain keys located in the first and second lines aresimultaneously input, the key in the first line is set to have thehigher priority. When certain keys located in the second and third linesare simultaneously input, the key in the second line is set to have ahigher priority.

In a second method for setting priority when two keys located in thesame line are simultaneously input and one of the keys is a navigationkey, the navigation key is set to have a higher priority. For example,if one of two keys which are simultaneously input in each line of FIG. 4is a navigation key, such as the key in the second column of the firstline, the key in the first column of the second line, the key in thethird column of the second line and the key in the second column of thethird line, the navigation key is set to have a higher priority.

In a third method for setting priority, when three or more keys aresimultaneously input and, if the each key is located in a differentline, the key is the upper line has priority and a navigation key in theupper line is set to have a highest priority.

A key input error prevention algorithm using the first, second and thirdmethods for setting priorities will now be explained. FIG. 5 is a flowchart illustrating a key input error prevention algorithm according to afirst embodiment of the present invention.

As illustrated in FIG. 5, when controller 105 detects two or more keyinput signals at the same time (S101), the controller determines thepositions, or line and column, of the detected keys (S102) and setspriorities for each key according to the priority setting methods(S103).

Once the priorities for each detected key are set, the controller 105determines the one key having the highest priority of the detected keys(S104). Accordingly, a key input error related to two or more keyssimultaneously input is prevented.

A key input error prevention algorithm in accordance with a secondembodiment of the present invention prevents the key input error bydetermining the key input that a user desires according to a capacitancelevel of a signal generated when touching a keypad region 201-209.

FIG. 6 illustrates a lateral end portion of typical user's finger.Generally, an end of a person's finger, as illustrated in FIG. 6, has anapproximately oval shape and particularly, a center portion 601 of afinger has a convex shape.

Therefore, two cases are defined for analyzing key input methodsaccording to finger shape. The first case, as illustrated in FIG. 7, isa key input using a convex portion of a finger. The second case, asillustrated in FIG. 8, is a key input using an end portion of a finger.

A contact portion between a finger and a keypad according to the keyinput methods illustrated in FIGS. 7 and 8 will now be described. FIG. 7illustrates a first key input method according to finger shape and FIG.8 illustrates a second key input method according to finger shape.

As illustrated in FIG. 7, when inputting a key using a convex portion P1of a finger, the convex portion directly contacts with the keypad, withother portions P2 and P3 spaced slightly apart from the keypad withoutdirectly contacting the keypad, Similarly, as illustrated in FIG. 8,upon inputting a key using an end portion P4 of a finger, the endportion directly contacts the keypad with the other portion P5 includingthe convex portion P1 of the finger spaced slightly apart from thekeypad without directly contacting the keypad.

Owing to the characteristics, a difference may be generated a between acapacitance signal output by a touch sensor due to the portion, forexample convex portion P1 of the finger, that directly makes contactwith the keypad and capacitance signals output by corresponding touchsensors due to the portions, P2 and P3 of the finger, which do notcontact the keypad. As illustrated in FIG. 9, the capacitance signal ofportion P1 is larger than the capacitance signals of the portions P2 andP3. In other words, a higher level signal is output when a contactdistance between the finger and the keypad is smaller and a contact areabetween the finger and the keypad is wider.

Therefore, the present invention determines the key input by comparingthe sizes of the capacitance signals when two or more keys are input.FIG. 10 is a flow chart illustrating a key input error preventionalgorithm in accordance with a second embodiment of the presentinvention.

As illustrated in FIG. 10, when the controller 105 detects two or morekey input signals at the same time (S201), the controller compareslevels of the corresponding key input signals (S202) to determine thekey input signal having the highest level (S203). The input signalrefers to a capacitance signal output from a touch sensor correspondingto each key of the keypad.

The key input is determined as the key of which the key input signal hasthe highest level (S204). Accordingly, a key input error related to twoor more keys are simultaneously input is prevented.

However, the difference in levels between the key input signals is onlyobtained at the initial moment a key is input. For a user who is apt topress a key habitually, a whole finger may be contacted with the keypadafter a certain time and, accordingly, the difference in levels betweenthe key input signals may not be generated.

A key input error prevention algorithm in accordance with a thirdembodiment of the present invention determines a key input based on adifference in times that a finger contacts the keypad. A key, which hasmore quickly output a key input signal having a higher level than areference level is determined as having been input.

Referring to FIG. 11, it can be noticed that the level of the key inputsignal of the portion P1, where the finger first contacts the keypad,reaches a reference level Ref earlier by a time t1 than the level of thekey input signal of the portions P2 and P3, where the finger contactsthe keypad later, reaches the reference level Ref.

Therefore, upon inputting two or more keys, the present inventiondetermines which key has been input by comparing the times at which thelevel of the corresponding key input signals reach the reference levelRef. FIG. 12 is a flow chart illustrating a key input error preventionalgorithm in accordance with a third embodiment of the presentinvention.

As illustrated in FIG. 12, when detecting two or more key input signalsat the same time (S301), the controller 105 compares the times at whichthe levels of the key input signals reach a reference level (S302) inorder to detect the key input signal that reaches the reference level inthe shortest time (S303). The key input signal denotes a capacitancesignal output by a touch sensor

The controller 105 detects the key input signal that reaches thereference level in the shortest time to determine that the keycorresponding to that key input signal has been input (S304).Accordingly, the key input error related to two or more keyssimultaneously input can be prevented.

The key input error prevention algorithms of the first three embodimentsillustrated in FIGS. 5, 10 and 12 are directed to preventing structuralerrors generated due to a narrow interval between keys of the keypadresulting from miniaturization of the terminal. However, applying thesame key sensitivity to every key that is not associated with a taskperformance may also generate key input errors.

For example, although certain keys, such as a navigation key, arerelated to specific tasks, such as a game, a menu selection task orplaying multimedia, the same sensitivity is applied when detecting thata key not related to a specific task has been input, such as acommunication key (SEND), a task clear key (CLR) or a phone numbersearching key. Therefore, the detection of an unexpected key mayinterrupt performance of the current task.

A key input error prevention algorithm in accordance with a fourthembodiment of the present invention is based on a classification of keysinto keys related to tasks that are currently being performed and keysnot related to tasks currently being performed. The sensitivities of thekeys not related to tasks currently being performed are adjusted to below in order to prevent key input error. In other words, keys that arenot related to tasks that are currently being performed are determinedas having been input only when the keys are input over a normal keyinput time.

The key sensitivity denotes a time during which a key input signalhaving a level higher than a threshold level is continuously maintained.Therefore, if it is assumed that a normal key sensitivity is 100 ms, thesensitivities of keys that are not related to the tasks currently beingperformed may be lowered by 300 ms in order to prevent the key inputerror.

For example, if a game task for which navigation keys are usually usedis currently being performed, the normal key sensitivity is maintainedfor the navigation keys, but the key sensitivity is adjusted lower forkeys, such as the clear key (CLR) and the communication key (SEND),which are not related to performing the game task. In related artmethods, when a finger contacts the keys not related to performing thegame task, such as CLR or SEND, while the game task is performed, themobile communications terminal may clear the game being performed andtransition to a standby state or transition to a mode for callcommunication. According to the method of the present invention, when afinger does not continuously contact the key not related to performingthe game task for a period of time that exceeds the adjusted keysensitivity, such as 300 ms, the controller 105 does not determine thatthe key has been input and the game continues uninterrupted.

FIG. 13 is a flow chart illustrating a key input error preventionalgorithm in accordance with a fourth embodiment of the presentinvention. As illustrated in FIG. 13, the controller 105 determines atask that is currently being performed (S401), and identifies keysrelated to the task and keys not related to the task (S402). Informationrelated to each key related to the task is stored in the memory 103. Thecontroller 105 refers to the key information stored in the memory 103 toadjust sensitivities of keys which are not related to the task currentlybeing performed to be lower than a normal key sensitivity (S403).

When a key input signal is detected (S404), the controller 105determines that the key has been input only when the key input signal iscontinuously maintained over the designated sensitivity (S405 and S406).For a key not related to the task currently being performed, thedesignated key sensitivity will be a longer period of time correspondingto the lower sensitivity. The key input signal denotes a capacitancesignal output from a touch sensor corresponding to each key of thekeypad. Therefore, the present invention can prevent the key input errordue to inputting keys that are not related to the task currently beingperformed

In addition to the key input errors resulting from the simultaneousinput of more than one key to which the previous embodiments of theinvention are directed, key input errors may be generated due to staticelectricity generated while carrying the terminal, static electricitygenerated from a human body while operating the terminal, noisegenerated by peripheral sources such as electrical equipment or a carpetthat generates electromagnetic waves or while charging the terminal.This may be more prevalent for a mobile communication terminal having atouch-type key input unit rather than a pressing type key input unit,which generates electromagnetic waves or while charging the terminal.

A key input error prevention algorithm in accordance with a fifthembodiment of the present invention is based on identifying anddifferentiating key input signals generated by static electricity orelectrical noise from normal key input signals, thereby preventing thestatic electricity or electrical noise from being recognized as a keyinput signal. FIG. 14 illustrates a comparison of a normal key inputsignal, static electricity and a noise signal.

The normal key input signal has a certain gradient θ1, as illustrated inFIG. 14A, since the key input signal is generated from the moment afinger approaches a key and then the level rises up to its highestlevel. An error range of the gradient θ1 is not great, although itdiffers according to the speed with which a user inputs keys, since thekey input speed with which a user normally inputs keys is limited.

On the other hand, a signal input due to static electricity is generatedsuddenly, as in FIG. 14B, and time for the signal to reach its highestlevel is short. Accordingly, the input signal due to static electricityhas a more drastic gradient θ2 as compared to the normal key inputsignal, such that θ2>θ1.

Therefore, the method of the present invention does not determine adetected input signal as a key input signal when it is determined thatthe gradient θ2 of the input signal is greater than the gradient of anormal key input signal. In this way, the present invention does notdetermine an input signal due to static electricity as a key inputsignal, thereby preventing key input error.

Each gradient θ1 and θ2 can be determined according to a rise time ofthe input signal or, as illustrated in FIGS. 14A and 14B, T=t4−t3)= froma time t3 when the level of the input signal starts rising to a time t4when the level of the input signal reaches a designated reference levelRef. As illustrated in FIGS. 14A and 14B, the input signal due to staticelectricity has a much shorter rise time than a normal key input signal.Each time t3 and t4 can be obtained using an inner timer 106 of theterminal.

When a normal key input signal contains noise having a certain frequencyand level, as illustrated in FIG. 14C, the level of the key input signalmay vary, thereby causing a key input error. According to the presentinvention, when the level of a key input signal varies within a certainrange, the level of the key input signal is determined based upon anaverage value Avr in order to prevent a key input error.

FIG. 15 is a flow chart illustrating a key input error preventionalgorithm in accordance with a fifth embodiment of the presentinvention. As illustrated in FIG. 15, when the level of the signal inputthrough a key input signal detecting port starts rising, the controller105 detects the starting time t3 and a time t4 when the level of the keyinput signal reaches a designated reference level Ref (S501 throughS504).

Next, the controller 105 calculates the rise time (T=Bt4−t3) of theinput signal according to the determined times t4 and t3 (S505) and thendivides the reference level Ref by the calculated rise time T of theinput signal in order to calculate the gradient θ2 for the input signal(S506). The controller 105 then compares the gradient θ1 of the normalkey input signal stored in the memory 103 to the calculated gradient θ2of the input signal (S507).

If the calculated gradient θ2 of the input signal is greater than thegradient θ1 of the normal key input signal (S508), the controller 105does not determine the input signal as a key input signal (S509). If thecalculated gradient θ2 of the input signal is less than or equal to thegradient θ1 of the normal key input signal, the controller 105determines the input signal as a normal key input signal (S510).

Each embodiment of the key input error prevention algorithm has beenexplained with regard to single generated error. However, embodiments ofthe key input error prevention algorithms according to the presentinvention may be combined or applied to prevent key input errors whenseveral input signals are simultaneously generated.

As described herein, key input errors can be prevented using thealgorithms of the present invention in a mobile communications terminalhaving a touch-type key input unit even when the keys of the key inputunit are arranged at narrower intervals. The present inventionfacilitates increased user convenience and miniaturization of theterminal.

As the present invention may be embodied in several forms withoutdeparting from the spirit or essential characteristics thereof, itshould also be understood that the above-described embodiments are notlimited by any of the details of the foregoing description, unlessotherwise specified, but rather should be construed broadly within itsspirit and scope as defined in the appended claims, and therefore allchanges and modifications that fall within the metes and bounds of theclaims, or equivalence of such metes and bounds are therefore intendedto be embraced by the appended claims.

The foregoing embodiments and advantages are merely exemplary and arenot to be construed as limiting the present invention. The presentteaching can be readily applied to other types of apparatuses. Thedescription of the present invention is intended to e illustrative, andnot to limit the scope of the claims. Many alternatives, modifications,and variations will be apparent to those skilled in the art. In theclaims, means-plus-function clauses are intended to cover the structuredescribed herein as performing the recited function and not onlystructural equivalent but also equivalent structures.

1. A mobile communications terminal comprising: a keypad having aplurality of touch keys and touch sensor units for sensing key inputsreceived from touching of the plurality of touch keys, and outputting akey input signal according to a sensed key input; and a controllerdetecting key input signals corresponding to two or more of theplurality of touch keys input via the keypad within a predetermined timeinterval, determining a priority for each of the plurality of the touchkeys, and recognizing one of the two or more of the plurality of touchkeys as a key input according to the determined priority, wherein thecontroller: determines a task which is currently being performed;identifies a first touch key among the plurality of touch keys that isnot related to the task currently being performed; identifies a secondtouch key among the plurality of touch keys that is related to the taskcurrently being performed; adjusts a sensitivity level of the firsttouch key to be lower than a sensitivity level of the second touch key;detects a key input signal corresponding to each of the plurality oftouch keys; and determines a touch key having a highest sensitivitylevel corresponding to the detected key input signal as the key input.2. The terminal of claim 1, further comprising: an analog to digital(A/D) converter converting the key input signal output from theplurality of touch sensor units into a digital signal; a timer detectingtime information related to the key input signal; and a memory storingthe priority set for each of the plurality of touch keys.
 3. Theterminal of claim 1, wherein the keypad comprises: a region havingactual keys or representing functions and positions of keys at a surfaceof a main body case; and touch sensors corresponding to each of theactual keys mounted under the plurality of actual keys or mounted atspecific regions of the keypad.
 4. The terminal of claim 1, wherein thecontroller determines the priority set for each of the two or more ofthe plurality of touch keys to accept a key input having a highestpriority among the two or more of the plurality of touch keys.
 5. Theterminal of claim 1, wherein the controller measures a period of timethat the key input signal is continuously maintained above a specificlevel and determines a touch key corresponding to the key input signalas the key input when the measured period of time exceeds a period oftime preset according to a sensitivity level.
 6. The terminal of claim1, wherein the controller adjusts a sensitivity level such that a lengthof time for which the sensitivity level of the key input signalcorresponding to the first touch key is continuously maintained above apredetermined level is longer than a length of time corresponding to thesecond touch key.
 7. The terminal of claim 6, wherein the controllerdetects a maximum level and a minimum level within which the key inputsignal varies and determines a period of time for which the key inputsignal is maintained according to an average value of the maximum andminimum levels.
 8. The terminal of claim 1, wherein the controlleradjusts a sensitivity level by setting a predetermined level, which thesensitivity level of the key input signal corresponding to the firsttouch key should exceed, higher than the sensitivity level of the secondtouch key.
 9. A method for detecting a key input in a mobilecommunication terminal, the method comprising: determining a task whichis currently being performed; identifying a first touch key that is notrelated to the task currently being performed; identifying a secondtouch key that is related to the task currently being performed;adjusting a sensitivity level associated with the first touch key to belower than a sensitivity level associated with the second touch key;detecting a key input signal corresponding to each of a plurality oftouch keys within a predetermined period of time; and determining atouch key corresponding to a detected key input signal having a highestsensitivity level as a touch key input.
 10. The method of claim 9,wherein determining the touch key input according to the sensitivitylevel comprises: measuring a period of time for which a level of the keyinput signal is continuously maintained above a predetermined level; anddetermining the touch key corresponding to the key input signal as thetouch key input if the measured period of time exceeds a specific timepreset according to the sensitivity level.
 11. The method of claim 10,wherein measuring the period of time for which the level of the keyinput signal is continuously maintained comprises: detecting a maximumlevel and a minimum level of the key input signal; and determining theperiod of time for which the key input signal is continuously maintainedaccording to an average value of the maximum and minimum levels.
 12. Themethod of claim 9, wherein adjusting the sensitivity level associatedwith the first touch key comprises: adjusting a period of time for whichthe level of the key input signal is continuously maintained above apredetermined level to be longer than a period of time corresponding tothe second touch key.